#define _CRT_SECURE_NO_WARNINGS 1

#include <stdio.h>

int main() {

    int sum = 0, grade;

    for (int i = 0; i < 5; i++)

    {

        scanf("%d", &grade);

        sum += grade;

    }

    printf("%.1f", sum / 5.0);

    return 0;

}